content: /* Copyright (C) 2016-2018 Alibaba Group Holding Limited
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
      http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  ==============================================================================*/
  
  // Protocol Buffers - Google's data interchange format
  // Copyright 2013 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package com.google.protobuf.nano;
  
  import java.io.IOException;
  import java.util.Arrays;
  
  /**
   * Abstract interface implemented by Protocol Message objects.
   *
   * @author wink@google.com Wink Saville
   */
  public abstract class MessageNano {
      protected volatile int cachedSize = -1;
  
      /**
       * Get the number of bytes required to encode this message.
       * Returns the cached size or calls getSerializedSize which
       * sets the cached size. This is used internally when serializing
       * so the size is only computed once. If a member is modified
       * then this could be stale call getSerializedSize if in doubt.
       */
      public int getCachedSize() {
          if (cachedSize < 0) {
              // getSerializedSize sets cachedSize
              getSerializedSize();
          }
          return cachedSize;
      }
  
      /**
       * Computes the number of bytes required to encode this message.
       * The size is cached and the cached result can be retrieved
       * using getCachedSize().
       */
      public int getSerializedSize() {
          int size = computeSerializedSize();
          cachedSize = size;
          return size;
      }
  
      /**
       * Computes the number of bytes required to encode this message. This does not update the
       * cached size.
       */
      protected int computeSerializedSize() {
        // This is overridden if the generated message has serialized fields.
        return 0;
      }
  
      /**
       * Serializes the message and writes it to {@code output}.
       *
       * @param output the output to receive the serialized form.
       * @throws IOException if an error occurred writing to {@code output}.
       */
      public void writeTo(CodedOutputByteBufferNano output) throws IOException {
          // Does nothing by default. Overridden by subclasses which have data to write.
      }
  
      /**
       * Parse {@code input} as a message of this type and merge it with the
       * message being built.
       */
      public abstract MessageNano mergeFrom(CodedInputByteBufferNano input) throws IOException;
  
      /**
       * Serialize to a byte array.
       * @return byte array with the serialized data.
       */
      public static final byte[] toByteArray(MessageNano msg) {
          final byte[] result = new byte[msg.getSerializedSize()];
          toByteArray(msg, result, 0, result.length);
          return result;
      }
  
      /**
       * Serialize to a byte array starting at offset through length. The
       * method getSerializedSize must have been called prior to calling
       * this method so the proper length is know.  If an attempt to
       * write more than length bytes OutOfSpaceException will be thrown
       * and if length bytes are not written then IllegalStateException
       * is thrown.
       */
      public static final void toByteArray(MessageNano msg, byte[] data, int offset, int length) {
          try {
              final CodedOutputByteBufferNano output =
                  CodedOutputByteBufferNano.newInstance(data, offset, length);
              msg.writeTo(output);
              output.checkNoSpaceLeft();
          } catch (IOException e) {
              throw new RuntimeException("Serializing to a byte array threw an IOException "
                      + "(should never happen).", e);
          }
      }
  
      /**
       * Parse {@code data} as a message of this type and merge it with the
       * message being built.
       */
      public static final <T extends MessageNano> T mergeFrom(T msg, final byte[] data)
          throws InvalidProtocolBufferNanoException {
          return mergeFrom(msg, data, 0, data.length);
      }
  
      /**
       * Parse {@code data} as a message of this type and merge it with the
       * message being built.
       */
      public static final <T extends MessageNano> T mergeFrom(T msg, final byte[] data,
              final int off, final int len) throws InvalidProtocolBufferNanoException {
          try {
              final CodedInputByteBufferNano input =
                  CodedInputByteBufferNano.newInstance(data, off, len);
              msg.mergeFrom(input);
              input.checkLastTagWas(0);
              return msg;
          } catch (InvalidProtocolBufferNanoException e) {
              throw e;
          } catch (IOException e) {
              throw new RuntimeException("Reading from a byte array threw an IOException (should "
                      + "never happen).");
          }
      }
  
      /**
       * Compares two {@code MessageNano}s and returns true if the message's are the same class and
       * have serialized form equality (i.e. all of the field values are the same).
       */
      public static final boolean messageNanoEquals(MessageNano a, MessageNano b) {
          if (a == b) {
              return true;
          }
          if (a == null || b == null) {
              return false;
          }
          if (a.getClass() != b.getClass()) {
            return false;
          }
          final int serializedSize = a.getSerializedSize();
          if (b.getSerializedSize() != serializedSize) {
              return false;
          }
          final byte[] aByteArray = new byte[serializedSize];
          final byte[] bByteArray = new byte[serializedSize];
          toByteArray(a, aByteArray, 0, serializedSize);
          toByteArray(b, bByteArray, 0, serializedSize);
          return Arrays.equals(aByteArray, bByteArray);
      }
  
      /**
       * Returns a string that is (mostly) compatible with ProtoBuffer's TextFormat. Note that groups
       * (which are deprecated) are not serialized with the correct field name.
       *
       * <p>This is implemented using reflection, so it is not especially fast nor is it guaranteed
       * to find all fields if you have method removal turned on for proguard.
       */
      @Override
      public String toString() {
          return MessageNanoPrinter.print(this);
      }
  
      /**
       * Provides support for cloning. This only works if you specify the generate_clone method.
       */
      @Override
      public MessageNano clone() throws CloneNotSupportedException {
          return (MessageNano) super.clone();
      }
  }
  